Mayor Michael Bloomberg says he wants to take a closer look at the Buildings Department.

Thirteen people have died in construction accidents in the first three and a half months of the year — already one more death than all of 2007.

Last week a window installer fell nine stories to his death when his safety strap failed.

Seven others died in a crane collapse last month, when a crane fell from a construction site in Turtle Bay.

Mayor Bloomberg wants to know what's behind the spike.

"If there's more construction, it makes common sense that you'd probably have more accidents or mistakes made, but that's not an excuse and I'm looking into it,” said Bloomberg.

Bloomberg says he'll look into whether the DOB has done everything it could do to prevent the accidents.

Buildings Commissioner Patricia Lancaster says her department had improperly issued a building permit at the site of the crane collapse, but that it did not play a role in the incident.